The present invention relates generally to microturbine power generating systems. More specifically, the present invention relates to a microturbine power generating system including a battery source for providing startup power.
The United States Electric Power Research Institute (EPRI), which is the uniform research facility for domestic electric utilities, predicts that up to 40% of all new electrical power generation could be provided by distributed generators by the year 2006. In many parts of the world lacking an electric infrastructure (e.g., transmission and distribution lines), the commercialization of distributed generators will be greatly expedited since central plants will not only cost more per kilowatt, but will also need expensive infrastructure installed to deliver power to consumers of electricity. In the United States and other countries already having the electric infrastructure, the small, multi-fuel, modular distributed microturbine generation units will allow consumers of electricity to choose the correct method of electric service. The small, multi-fuel, modular distributed microturbine generation units will also allow consumers of electricity to choose the most cost-effective electric service.
Small, multi-fuel, modular distributed microturbine generation units could help alleviate current afternoon "brownouts" and "blackouts" that are prevalent in many parts of the world. A simple, single moving part concept would allow for low technical skill maintenance. Low overall cost would allow for wide spread purchase in those parts of the world where capital is sparse.
For an example of a microturbine power generating system, see U.S. Pat. No. 4,754,607, which is assigned to the assignee of the present invention. The microturbine power generating system includes a turbine, a compressor and an electrical generator, with each device including a rotating component (e.g., a turbine wheel, a compressor wheel and a permanent magnet rotor).
Starting up the microturbine power generating system can be problematic. A separate starter motor could be used to turn the compressor until the microturbine power generating system is capable of sustaining combustion. In the alternative, the electrical generator could be used to turn the compressor during startup, as disclosed in the assignee's co-pending patent application U.S. Ser. No. 08/995,462 filed on Dec. 19, 1997. A switch/starter control is included to supply an excitation current to stator windings of the electrical generator, which turns the compressor until combustion can be sustained.
Using either approach, an external source of power is needed to operate the starter motor or to supply an excitation current to the stator windings of the electrical generator. U.S. Ser. No. 08/995,462 also discloses a battery for providing power to the switch/starter control. The battery is sized to the requirements of the system.
However, such a battery tends to have a high voltage. High-voltage batteries are difficult and potentially dangerous to handle. Large, high-voltage batteries are also uncommon and, therefore, are difficult to procure in large quantities. This would create problems for mass production of the microturbine power generating systems.